System for the preparation of metal sulfates via electrochemical dissolution

Abstract

A metal sulfate preparation system includes an electrochemical dissolution system having an anode electrode for containing a metal raw material, a cathode electrode, an electrolyte bath, a stirring device for mixing the electrolyte bath, a temperature control system, and a rectifier for providing a current at a constant voltage between the anode and cathode electrodes. The electrolyte bath has an inlet for receiving an initial acid or metal acid complex solution and an outlet for discharging the treated metal sulfate solution.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 713,702, filed on August 2, 2018, entitled “METAL SULFATE MANUFACTURING SYSTEM VIA ELECTROCHEMICAL DISSOLUTION,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to synthesizing metal sulfate solutions, and in particular to synthesizing metal sulfates from metal feedstocks. Background Art

[0004] Nickel and cobalt sulfates are commonly used as raw materials for lithium-ion battery cathode precursor materials, nickel metal hydride battery cathodes, and nickel-cadmium battery cathodes. Due to their limited supply, it is sometimes difficult or expensive to purchase metal sulfate products from the market. As a result, several companies synthesize metal sulfate solutions by dissolving more easily accessible metal products (such as nickel powder, nickel agglomerates, cobalt powder, and cobalt agglomerates) in sulfuric acid. However, the growth of the electric and hybrid vehicle market is expected to continue into the future, and has led to a shortage of metal powders and agglomerates in addition to sulfates.

[0005] The metal cathode market is larger than the metal powder and agglomerate market, making metal cathode materials more readily available. However, metal cathodes can be difficult to dissolve using sulfuric acid, especially dilute sulfuric acid, because the cathode has significantly less surface area exposed to the acid than in metal powder and agglomerate form.

[0006] Existing methods use high temperature, high pressure and high sulfuric acid concentration to dissolve metals by sulfuric acid. However, these methods require expensive equipment and additional safety measures, because dissolving at high pressure and acid concentration is inherently more dangerous. In addition, it is difficult to consume the residual acid in the metal sulfate solution prepared by sulfuric acid dissolution using conventional methods without long reaction times. High residual acid levels are undesirable for subsequent processing and require the addition of pretreatment steps. Summary of the invention

[0007] One embodiment is an electrochemical dissolution system and method for preparing water-based metal (nickel, cobalt, manganese, etc.) sulfate solutions from various metal products (cathodes, lumps, powders, etc.) using relatively dilute sulfuric acid. In this embodiment, an electrochemical dissolution apparatus having an anode and a cathode and an acid solution are used to synthesize a metal sulfate solution from a metal cathode, powder or lumps feedstock. In some embodiments, the electrochemical dissolution system allows the user to use a relatively lower concentration of sulfuric acid than conventional methods, and the resulting metal sulfate solution has a lower residual sulfuric acid concentration than existing systems.

[0008] In one aspect, an electrochemical dissolution system for dissolving a metal feedstock is described. The system includes an electrolyte bath container having an inlet, an outlet, a temperature control system, and is configured to contain an electrolyte solution. The system also includes a liquid permeable anode disposed within the bath container. The system also includes a cathode electrode surrounding the liquid permeable anode electrode. The system also includes a power source electrically connected to the liquid permeable anode electrode and the cathode electrode. In some embodiments of the system, the cathode electrode surrounds the liquid permeable anode electrode equally on all sides. In some embodiments, the system also includes an agitator configured to stir the electrolyte within the bath container.

[0009] In some embodiments, the liquid permeable anode comprises a basket shape, a sandwich shape, or a tray shape. In some embodiments, the liquid permeable anode electrode comprises at least one of platinum, platinum-coated titanium, and iridium-coated titanium. In some embodiments, the system further comprises a metal feedstock immersed in the electrolyte bath and held by the liquid permeable anode electrode. In some embodiments, the metal feedstock comprises at least one of a nickel cathode, a nickel agglomerate, a cobalt cathode, and a cobalt agglomerate. In some embodiments, the liquid permeable anode electrode comprises an anode electrode body, and the anode electrode body comprises at least one of a mesh material and a perforated material.

[0010] In some embodiments, the cathode electrode comprises at least one of: platinum, platinum-coated nickel, and nickel. In some embodiments, the cathode electrode comprises a cathode electrode body comprising at least one of: a corrugated material, a sponge material, and an embossed material.

[0011] In some embodiments, the electrolyte bath container comprises an electrolyte. In some embodiments, the electrolyte comprises an acid. In some embodiments, the acid is sulfuric acid. In some embodiments, the acid concentration is between about 1 M and about 3 M. In some embodiments, the electrolyte bath agitator comprises at least one of a mechanical agitator, a magnetic stir bar, a liquid circulator, and an air agitator.

[0012] In another aspect, a method of using an electrochemical dissolution system is described. The method includes: applying a voltage between a liquid permeable anode electrode and a cathode electrode; providing fresh electrolyte solution to an electrolyte bath container through an inlet; and removing a treated solution from the electrolyte bath container through an outlet.

[0013] In some embodiments of the method, the fresh electrolyte solution has a metal concentration that is less than the metal concentration of the treated solution. In some embodiments, the method further comprises controlling the temperature of the electrolyte bath container between about 35° C. and about 60° C. using a temperature control system. In some embodiments, a voltage between about 2.0 V and about 3.5 V is applied. In some embodiments, a voltage between about 0.1 V and about 1 V is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A prior art system for dissolving solid metallic material into a concentrated acid solution is shown.

[0015] Figure 2 Typical results for a prior art system when using a low surface area metal material such as a metal cathode as the metal feedstock are shown.

[0016] Figure 3 A prior art system for dissolving a solid metallic material / anode into a concentrated acid solution in the presence of an applied electric field generated by a power source is shown.

[0017] Figure 4 Typical results for a prior art system when using a low surface area metallic material such as a solid metal cathode as the anode are shown.

[0018] Figure 5 An electrochemical dissolution system for dissolving a metal feedstock into an acid solution according to disclosed embodiments of the present disclosure is shown, in accordance with certain embodiments of the present disclosure.

[0019] Figure 6 An electrochemical dissolution system for dissolving a metal feedstock into an acid solution according to disclosed embodiments of the present disclosure is shown, in accordance with certain embodiments of the present disclosure.

[0020] Figure 7 The operational results of using the system according to the embodiment of the present disclosure are shown.

[0021] Figure 8 is a flow chart illustrating the operation of an electrochemical metal dissolution system according to certain embodiments of the present disclosure.

[0022] Fig. 9 is a flow chart illustrating the operation of an electrochemical metal dissolution system according to certain embodiments of the present disclosure.

[0023] By referring to the detailed description below, the embodiments of the present disclosure and its advantages will be best understood. It should be understood that the same reference numerals are used to identify similar elements illustrated in one or more of the accompanying drawings, wherein the figures in the accompanying drawings are for illustrating embodiments of the present disclosure rather than for limiting the present disclosure.

[0024] Fig.10 is a graph showing current versus voltage for a Ni pellet dissolved using an embodiment of the system of the present disclosure.

[0025] Fig.11 is a graph showing current versus voltage for a Ni cathode nugget dissolved using an embodiment of the system of the present disclosure.

[0026] Fig.12 is a graph showing dissolution of Ni pellets using an embodiment of the disclosed system.

[0027] Fig.13 is a graph showing the current versus voltage characteristics of Ni electrochemical dissolution using a 2M sulfurized acid electrolyte solution at 60°C using an embodiment of the disclosed system. DETAILED DESCRIPTION

[0028] The present disclosure describes a preparation system and method for synthesizing metal sulfate solutions from metal raw materials. This can be used as part of a recycling process in which the metal raw materials are obtained from components such as consumed battery cathodes. The metal raw materials can include nickel cathodes, nickel lumps, cobalt cathodes, and cobalt lumps, which have improved process costs and reaction times compared to conventional methods. The present disclosure also describes an electrochemical dissolution system for preparing water-based metal (nickel, cobalt, manganese, etc.) sulfate solutions taken from metal raw materials.

[0029] In one embodiment, the electrochemical dissolution system includes an anode electrically connected to a cylindrical basket for containing a metal raw material. A cylindrical cathode is configured to surround the anode basket at a predetermined distance from the anode, for example, wherein the cathode includes a cylindrical shape having a diameter slightly larger than the cylindrical basket connected to the anode. The anode and cathode are immersed in a weakly acidic preparation (such as sulfuric acid), and an electric potential is placed between the anode and the cathode. The electric potential helps to decompose the metal raw material in the anode basket, and the acidic preparation can flow through the raw material to further cause digestion of the metal raw material, thereby forming a metal sulfate aqueous solution. Compared with conventional methods, the use of this configuration allows a lower concentration of sulfuric acid to flow through the metal raw material and be utilized, so that the residual sulfuric acid concentration after treatment is weaker.

[0030] Embodiments of the electrochemical dissolution system separate the anode and / or cathode electrical connections from the metal feedstock by placing the feedstock in a basket and not directly connecting the metal feedstock to the electrodes. This provides a practical and cost-effective method for electrochemical metal dissolution without the risk of disconnecting the contact between the metal material and the electrical leads while the metal material is being digested in an acidic solution.

[0031] In some embodiments, the anode electrode may be formed by or electrically connected to a body that holds a metal raw material. The body may be a basket and may be liquid permeable so that the liquid can pass from the outside of the electrode through the anode electrode to the inside of the electrode. In some embodiments, the liquid is an aqueous solution and / or an organic solution. In some embodiments, the liquid permeable anode electrode is shaped or configured to hold the metal raw material inside the electrode. In some embodiments, the liquid permeable anode electrode is shaped into a basket-type shape, a sandwich-type shape, or a tray-type shape. In some embodiments, the liquid permeable anode electrode includes a body that is at least one of the following: a mesh body and a perforated metal body. In some embodiments, the liquid permeable anode electrode is shaped into a mesh basket or similar container of a cylindrical, cubic, triangular, or other geometric shape. In some embodiments, the anode electrode includes an insoluble material that is chemically and electrically inert during operation of the system. In some embodiments, the anode electrode is configured to physically hold or immerse the metal raw material in a solution while supplying an electric current until the metal raw material is substantially or completely dissolved. In some embodiments, the anode electrode includes at least one of the following or is formed by at least one of the following: platinum, platinum-coated titanium, or iridium oxide-coated titanium.

[0032] In one embodiment, the cathode electrode of the system is positioned to surround the anode electrode. In some embodiments, the cathode electrode partially, substantially or completely surrounds the anode electrode. In some embodiments, the cathode electrode partially, substantially or completely surrounds the surface area of ​​the anode electrode. In some embodiments, the cathode electrode surrounds the anode electrode greater than or greater than about 50%, 75%, 80%, 90%, 95%, 97%, 98% or 99%, or any value range therebetween. In some embodiments, the cathode electrode surrounds the anode electrode equidistantly so that the adjacent positions of the cathode electrode and the anode electrode have the same or substantially the same distance. For example, the cathode can have a cylindrical shape with a diameter slightly larger than that of a cylindrical anode. In some embodiments, the distance between the cathode adjacent position and the anode adjacent position is or is about 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 1cm or 2cm, or any value range between the above items. In some embodiments, the cathode electrode includes an insoluble metal that is chemically and electrically inert during the operation of the system. In some embodiments, the cathode electrode includes the same metal dissolved from the metal raw material during the operation of the system. In some embodiments, the cathode electrode has a relatively large surface area to maximize current density during operation. In some embodiments, the surface area of ​​the cathode is or is about 50 cm 2 、75cm 2 、95cm 2 , 100cm 2 、150cm 2 , 200cm 2 、300cm 2 、400cm 2 , 500cm 2 , 1000cm 2 , 2000cm 2 or 5000cm 2 , or any range of values ​​therebetween. In some embodiments, the surface area of ​​the cathode electrode is or is about 1 m 2 、5m 2 、10m 2 、25m 2 、50m 2 、75m 2 、95m 2 、100m 2 、150m 2 、200m 2 、300m 2 、400m 2 、500m 2 , 1000m 2 , 2000m 2 or 5000m 2, or any range of values ​​therebetween. It should be understood that the surface area of ​​the cathode electrode will scale according to the system size and production capacity. In some embodiments, the cathode electrode comprises at least one of: platinum, platinum-coated metal, cobalt, and nickel. In some embodiments, the cathode electrode comprises a body that is at least one of: a corrugated plate-type body, a sponge metal-type body, and an embossed metal-type body. In some embodiments, the cathode electrode is a liquid permeable cathode electrode.

[0033] The electrochemical dissolution system may include an electrolyte solution. In some embodiments, the electrolyte includes at least one of an acid and a metal sulfate. In some embodiments, the acid is selected from at least one of sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid and chloric acid. In some embodiments, the electrolyte includes a dilute sulfuric acid solution or a dilute metal sulfate solution. In some embodiments, the electrolyte includes an acid concentration (such as sulfuric acid) of or about: 0.1M, 0.25M, 0.5M, 0.75M, 1M, 1.25M, 1.5M, 1.75M, 2M, 2.25M, 2.5M, 2.75M, 3M, 3.5M, 4M and 5M, or any range of values ​​therebetween. In some embodiments, the electrolyte solution includes a sulfuric acid concentration of or about between 1M and 3M.

[0034] In one embodiment, the electrochemical dissolution system includes a fluid inlet for providing a fresh electrolyte solution and an outlet for extracting a treated electrolyte solution from the system. In some embodiments, the system operates as a continuous system, wherein a fresh electrolyte solution (e.g., such as sulfuric acid or a dilute metal sulfate solution) flows continuously into the electrochemical dissolution system through the fluid inlet and mixes with the existing electrolyte solution in the system. In some embodiments, the electrolyte in the electrochemical dissolution system is maintained by an electrolyte bath container surrounding the anode and cathode assemblies. When a new electrolyte solution is added through the fluid inlet, a treated solution (e.g., such as a concentrated product metal sulfate solution) can be continuously discharged from the electrochemical dissolution system.

[0035] In some embodiments, the fresh electrolyte solution comprises a dilute sulfuric acid solution or a dilute metal sulfate solution. In some embodiments, the process solution comprises a concentrated metal sulfate solution. In some embodiments, the inlet and / or outlet has a flow rate of or about 5 mL / hr, 10 mL / hr, 15 mL / hr, 20 mL / hr, 25 mL / hr, 30 mL / hr, 50 mL / hr, 100 mL / hr, or 1000 mL / hr, or any range of values ​​therebetween. In some embodiments, the inlet and / or outlet has a flow rate of or about 1 m 3 / hr、5m 3 / hr、10m 3 / hr、15m 3 / hr、20m3 / hr、25m 3 / hr、30m 3 / hr、50m 3 / hr、100m 3 / hr or 1000m 3 / hr, or any range of values ​​therebetween. It should be understood that the flow rate will be configured based on system size and production capacity. In some embodiments, the metal concentration of the fresh electrolyte solution (e.g., such as a diluted initial metal sulfate or sulfuric acid solution) is less than that of the treated solution (e.g., such as a final treated metal solution).

[0036] In one embodiment, the electrochemical dissolution system includes an electrolyte bath container containing an anode, a cathode, and an electrolyte solution. In some embodiments, the electrolyte bath container includes an insoluble material that is chemically and electrically inert during operation of the system. In some embodiments, the electrolyte bath container includes at least one of the following that is resistant to degradation by the acidic electrolyte solution: plastic, glass, or a glass-coated metal material.

[0037] The system may include a temperature control system to control the temperature of the electrolyte solution. The temperature control system may allow for higher current efficiency and more stable operation of the electrochemical dissolution system. In some embodiments, the temperature control system controls the temperature of the electrolyte solution in the electrolytic bath to or about 20°C, 23°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C, 90°C and 100°C, or any range of values ​​between the above items. For example, in some embodiments, the temperature control system controls the temperature of the electrolyte solution in the electrolytic bath to or about between 35°C and 60°C.

[0038] The system may include an electrolyte bath agitator. In some embodiments, the agitator may include a stirring device. In some embodiments, the stirring device may include at least one of the following: a mechanical agitator, a magnetic stirrer, a liquid circulator, and an air agitator. The agitator can be used to continuously mix the electrolyte solution and / or remove bubbles generated from the surface of the anode electrode and / or cathode electrode during operation. Electrochemical dissolution can form hydrogen and oxygen on the surface of the electrode, which may hinder the current density. Physically removing bubbles from the electrode with an agitator can help accelerate the dissolution reaction to form a more concentrated metal sulfate solution. In some embodiments, the agitator includes an insoluble material that is chemically and electrically inert during operation of the system.

[0039] The system may include a power supply, which is electrically connected to the anode electrode and the cathode electrode. In some embodiments, the power supply can provide a constant voltage and / or ampere. In some embodiments, the power supply can provide a variable voltage and / or ampere. In some embodiments, the power supply is a rectifier, which can provide a current with a constant voltage between the anode and the cathode. In some embodiments, the voltage applied by the power supply is greater than or approximately greater than 0V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1V, 1.5V, 2V, 2.2V, 2.4V, 2.5V, 2.6V, 2.8V, 3V, 3.5V, 4V and 5V or any value range between the above items. For example, in some embodiments, the power supply (for example, such as a rectifier) ​​is applied to or is approximately a voltage between 2.0V and 3.5V. As an additional example, in some embodiments, the power supply (for example, such as a rectifier) ​​is applied to or is approximately a voltage between 0.1V and 1V.

[0040] In some embodiments, the metal raw material in contact with the anode electrode can be dissolved and ionized by the applied voltage during operation of the system. The cathode electrode generates hydrogen gas through the hydrogen ions and electrons generated by the applied voltage. As a result, in some embodiments, metal sulfate is generated from the metal raw material and dilute sulfuric acid as given by the following reaction (in the case of nickel and sulfuric acid).

[0041] Overall reaction: Ni+H2SO4→NiSO4+H2

[0042] Anode: Ni→Ni 2+ +2e -

[0043] Cathode: 2H + +SO4 2- +2e - →H2+SO4 2-

[0044] In some embodiments, the present disclosure provides a system and method for dissolving a metal in an acidic solution, wherein the anode is not chemically or electrochemically dissolved during operation, and the anode provides continuous electrical contact with the metal material. Stirring or agitation removes the accumulated gas on the electrode surface, provides a uniform ion concentration, and prevents local concentration accumulation inside the anode electrode. The temperature control system can provide an optimal temperature for the electrolyte and operation to maximize the dissolution reaction rate. In some embodiments, the operating parameters of the system are configured to minimize the amount of residual acid.

[0045] Embodiments of the present disclosure can produce relatively high concentrations of metal sulfate solutions while minimizing the residual sulfuric acid concentration, making it very suitable for the needs of subsequent processes. In some embodiments, the concentration of the metal sulfate included in the electrolyte is or is about 0.1M, 0.25M, 0.5M, 0.75M, 1M, 1.25M, 1.5M, 1.75M, 2M, 2.25M, 2.5M, 2.75M, 3M, 3.5M, 4M and 5M, or any value range between the above items. In addition, compared with conventional methods, some embodiments of the present disclosure can use more dilute sulfuric acid as a sulfate source, thereby not requiring an additional acid concentration pretreatment step. In addition, compared with conventional sulfuric acid dissolution, some embodiments of the present disclosure require shorter reaction times, thereby allowing smaller and more cost-effective equipment sizes. In addition, some embodiments of the present disclosure improve the safety of conventional sulfuric acid dissolution systems, and do not require high temperature, high acid concentration and / or high pressure during the operation of the system. Furthermore, embodiments of the present disclosure may maintain the current load until metal dissolution is complete, in contrast to conventional electrochemical dissolution methods where the power supply is interrupted after the metal material is preferentially dissolved from the lead.

[0046] Prior art systems

[0047] Figure 1 A prior art system 100 for dissolving a solid metallic material 107 into a concentrated acid solution 105 is shown. Figure 1 The system 100 includes an electrolyte bath container 101, a temperature control system 102, a stirring device 103, a corresponding impeller 104, a concentrated acid solution 105 and a metal raw material 106. Figure 1 The illustrated system 100 operates without an electrical driving force, which facilitates the dissolution of the solid metallic material 107 .

[0048] Figure 1 The system 100 operates by solubilizing a solid metal feedstock 107 via chemical acid leaching, which is a process in which the solid metal is diffused into a solvent bath under favorable conditions of pressure, temperature, agitation, and acid concentration. Sulfuric acid is used as a leaching solvent because of its strong tendency to oxidize metals via a single displacement reaction, thereby producing hydrogen and metal sulfate species as reaction products. The temperature control system 102 allows a higher temperature to be set to increase the chemical reaction rate and solubility limit of the metal salt species. The stirring device 103 can provide agitation via an impeller 104 to increase the chemical reaction rate.

[0049] exist Figure 1In the operation of the system 100, the concentrated acid or metal acid complex solution 105 converts the solid metal material into a soluble metal salt material and releases hydrogen as a byproduct. The initial acid or metal acid complex solution becomes more metal-rich during operation because the initial metal raw material is converted into a soluble metal salt in the presence of high temperature, high pressure, stirring speed and acid concentration. The high pressure and acid concentration commonly used require additional measures to safely operate the reactor vessel and prevent chemical exposure.

[0050] Figure 2 Typical results found in a prior art system 100 when a low surface area metal material such as a metal cathode is used as the metal feedstock 106, and the concentration of metal dissolved into the concentrated acid solution 105 over the operating time of the system 100 is shown. Due to the small surface area of ​​the metal cathode, the metal dissolution rate is relatively low, and the resulting dissolved metal concentration in the solution increases slowly over time. The solubility limit of the metal species in the acidic solution generally varies between 100 g / L and 400 g / L, depending on the type of metal salt complex formed, the reaction pressure used, and the reaction temperature used. However, as Figure 2 As shown, system 100 typically does not achieve concentrations above 10 g / L without very long reaction times. Thus, not all low surface area metal materials can be chemically leached into the electrolyte solution due to the extremely long reaction times required.

[0051] Figure 3 Another prior art system 300 for dissolving a solid metallic material / anode 303 into a concentrated acid solution 305 in the presence of an applied electric field generated by a power source 302 is shown. Figure 3 The system in includes an electrolyte bath container 301, a power source 302, a solid metal material / anode electrode 303, a cathode electrode 304, and a concentrated acid solution 305. The solid metal material / anode electrode 303 is positively charged and collects electrons emitted by its oxidation under an applied potential. The cathode electrode 304 is negatively charged and releases electrons by reducing hydrogen ions in the solution to form hydrogen gas.

[0052] Figure 3 The system 300 operates by dissolving the solid metal material / anode electrode 303 via metal anodic dissolution, whereby a slow but spontaneous chemical dissolution process is actively driven by applying an applied potential between the solid metal material / anode electrode 303 immersed in a concentrated acid solution 305 and the cathode electrode 304. Figure 3 In the system 300, an electric field is applied between the solid metal material / anode electrode 303 and the cathode electrode 304 to convert the negatively charged acid counter ions (such as SO4 2-) are pulled toward the solid metal material / anode 303, where they interact with the M generated by oxidation of the solid metal material / anode 303. 2+ (M = metal, such as Ni, Co, etc.) ions combine. The electrons generated at the solid metal material / anode electrode 303 are driven by the power supply 302 to the cathode electrode 304 where they combine with hydrogen ions to form hydrogen gas.

[0053] exist Figure 3 In operation of the system 300, the electric potential generated by the power source 302 drives the conversion of the solid metal material / anode electrode 303 to a soluble metal salt species, and releases hydrogen as a byproduct. The initial acid or metal acid complex solution 305 becomes more metal-rich during operation because the solid metal material / anode electrode 303 is converted to a soluble metal salt in the presence of the electric field. Although the metal dissolution reaction begins to compete with water electrolysis at 1.23V, higher potentials are generally used to drive the reaction rate.

[0054] Figure 4 Typical results obtained from the system 300 when a low surface area metal material, such as a solid metal cathode material, is used in the system 300 are shown. Although initially, the metal concentration in the solution increases over time, the reaction rate slows before stopping due to the loss of electrical contact between the solid metal material / anode electrode 303 and the power supply 302. The reason for this loss of contact is that the solid metal material / anode electrode 303 preferentially dissolves in the uppermost region in the solution and at its interface with the electrical lead, causing the solid metal material / anode electrode 303 to physically break and fall into the acid solution 305. This physical break electrically isolates the solid metal material / anode electrode 303, thereby preventing further oxidation and metal dissolution.

[0055] Electrochemical Dissolution System

[0056] Figure 5 A cross-sectional view of an electrochemical dissolution system 500 for dissolving a metal feedstock into an acid solution is shown according to one embodiment of the present disclosure. Figure 6 Shows Figure 5 A top view of the system is shown. Figure 5 and Figure 6The electrochemical dissolution system 500 includes an electrolyte bath container 501, a temperature control system 502, an anode electrode 503, a cathode electrode 504, a solution agitator 505, a power supply 506, an acid solution 507, an inlet valve 508, an outlet valve 509, and a metal feedstock 510. The anode electrode 503 is positively charged and collects electrons emitted due to oxidation of the metal feedstock 510 when an electric potential is applied. The cathode electrode 504 is negatively charged and releases electrons by reducing hydrogen ions in the solution to form hydrogen gas. The agitator 505 can be at least one of the following: a mechanical agitator, a magnetic stirrer, a liquid circulator, or an air agitator, which continuously mixes the solution and removes bubbles generated during operation from the surfaces of the anode electrode and the cathode electrode. In the absence of an agitator, these generated bubbles will hinder the maximum current density and thereby hinder the dissolution rate by reducing the available surface area on the cathode electrode and the anode electrode. The temperature control system can be configured to maintain the solution temperature in the electrolyte bath container between 35°C and 60°C, although other temperatures and ranges are also within the scope of the present disclosure.

[0057] The electrochemical dissolution system 500 has uniquely structured electrodes to maximize its metal dissolution capabilities. The anode electrode 503 is liquid permeable and shaped as a cylindrical basket. In some embodiments, the basket is made of at least one of: platinum, platinum-coated titanium, or iridium oxide-coated titanium. In addition, the anode electrode 503 is chemically inert and does not react or dissolve with the electrolyte solution under the applied chemical potential. The anode electrode holds the metal feedstock 510 and structurally suspends it in the solution. The cathode electrode 504 is constructed as a cylindrical sheet equidistantly surrounding the anode electrode 503. The cathode electrode 504 can be made of at least one of: platinum, a platinum-coated metal, cobalt, and nickel.

[0058] The system 500 operates by dissolving a metal feedstock 510 (e.g., nickel or cobalt) via metal anode dissolution, whereby a slow but spontaneous chemical dissolution process is actively driven by applying an applied potential between an anode electrode 503 and a cathode electrode 504 immersed in an acid solution 507. In one embodiment, the anode electrode 503 does not contain a metal feedstock and is therefore not electrochemically dissolved during operation of the system. Instead, the anode electrode 503 maintains electrical contact with a power source 506 during the reaction, which allows the target metal material 510 to be completely dissolved. The inlet 508 and outlet 509 ports are located on opposite sides of the electrolyte bath container and can be configured to allow a continuously operated system. However, it should be recognized that the inlet and outlet of the system 500 can be located at different positions relative to each other and still be within the scope of the present disclosure.

[0059] like Figure 6As shown in the top view of the anode 503, the anode 503 is cylindrical and is located inside the cylindrical cathode 504. Each of these components is placed in a cylindrical bath container 501 including a heater 502. The position of the anode 503 is shown to be equidistant from the surrounding cathode 504 on all sides of its cylindrical shape. As used with respect to the cathode, the term "around" means that the cathode can be formed partially or completely around the anode. For example, the cathode can be a cylinder formed completely or mostly around a smaller cylindrical anode. In one embodiment, the cathode completely surrounds the circumference of the anode. In another embodiment, the cathode is 95%, 96%, 97%, 98%, 99% or more around the anode.

[0060] Figure 7 Shows Figure 5 and 6 Typical operating results of the system shown. The concentration of metal sulfate produced by the dissolution of the metal feedstock in solution increases over time and may eventually reach the solubility limit of the metal salt species in solution.

[0061] and Figure 1 Prior art system 100 and Figure 3 The electrochemical dissolution system 500 has operational advantages over the system 300 of FIG. For example, it has been found that the use of the electrochemical dissolution system 500 allows the metal feedstock to dissolve at a faster rate, resulting in a higher concentration of soluble metal (e.g., nickel or cobalt) species in the resulting treatment solution. In addition, the treated solution flowing out of the outlet of the electrochemical dissolution system 500 has a lower residual acid concentration, will operate well at standard atmospheric pressure, and can function using a lower initial acid concentration of the electrolyte.

[0062] The higher metal dissolution rate in the electrochemical dissolution system 500 most likely results from the electrode design, which allows a higher active electrode surface area to contact the metal feedstock, while the metal species 510 is in close proximity to the anode electrode 503, and the anode electrode 503 is in close proximity to the cathode electrode 504. The net effect was found to reduce the resistance experienced by the ionic species in the acid solution 507, thereby allowing relatively higher current density and current efficiency within the system.

[0063] The use of the electrochemical dissolution system 500 allows higher metal concentrations to be achieved because the anode electrode 503 is chemically inert and there is no risk of losing electrical contact with the power supply 506. This allows the system to operate indefinitely as long as fresh metal and acidic species are continuously provided to the system in the presence of an applied potential. It has been found that the system described herein can achieve metal dissolution rates close to 100% of the metal feedstock. Lower residual acid concentrations are found because of the high utilization of the acidic species 507 achieved in the process of converting the metal feedstock 510 into the metal salt species in the electrolyte. This allows the resulting treated acid solution to be immediately usable for further chemical processes because no additional pretreatment steps are required to use the treated acid solution in subsequent preparation steps.

[0064] Figure 8 is a flow chart illustrating the operation of an electrochemical metal dissolution system according to some embodiments. Figure 8 It is shown that in the first step, a metal feedstock is combined with an acidic substance (shown as sulfuric acid). Once these ingredients are combined in the first step, they can be placed in the system 500 to start electrochemical dissolution using an applied potential. Running this process results in obtaining metal sulfate from the metal feedstock.

[0065] Fig. 9 Shows relative to Figure 8 An embodiment of the method shown, wherein a chemical acid dissolution step is performed before the electrochemical dissolution step. Fig. 9 , the metal feedstock is first chemically dissolved in the absence of an electrical potential. Once the chemical dissolution stops or slows to an undesirably low value, an electrical potential is applied to initiate electrochemical dissolution, thereby producing a more concentrated metal sulfate solution.

[0066] Example

[0067] Example 1

[0068] Table 1 below shows the results of a first test using an electrochemical dissolution system operating in a constant current mode with a Ni cathode electrode nugget in a 2M sulfuric acid electrolyte solution. The test was used to infer the incremental decrease in the weight of the Ni cathode electrode nugget. The final pH of the electrolyte solution was 0.07 pH. No effective deposition of Ni on the cathode electrode was found. The overall electrical efficiency was found to be 84.0%.

[0069] Table 1

[0070] Time (hr) Voltage (V) Current (A) Temperature(℃) Ni concentration (g / L) 0 3 4.7 32 0 1 3 4.7 38 11.9 2 3 5 45 18.5 3 3 5 50 28.2 4 3 5 53 42.4

[0071] This example shows that the Ni concentration in the electrolyte solution increases from 0 g / l to 42.4 g / l over four hours at three volts.

[0072] Example 2

[0073] Table 2 shows the results of a second test using the disclosed system, which was run in a constant voltage mode using a Ni cathode electrode nugget in a 2M sulfuric acid electrolyte solution. The test was used to infer the incremental decrease in the weight of the Ni cathode electrode nugget. The final pH of the electrolyte solution was 0.22 pH. The total electrical efficiency was 77.9%. The efficiency of each voltage cycle was about 50%. A total of 2.1 g of Ni was found to be deposited on the cathode electrode. A total of 36.9 g of Ni was dissolved in the solution.

[0074] Table 2

[0075] Time (hr) Voltage (V) Current (A) Temperature(℃) Ni concentration (g / L) 0 - - 25 0 2 1.5 7 45 22.4 4 2 7.9 48 44.8 6 3 5.8 50 81.7 7 3.5 7.5 59 115

[0076] This example shows that the Ni concentration in the electrolyte solution increases from 0 g / l to 115 g / l over 7 hours at a voltage of 1.5 to 3.5 volts.

[0077] Example 3

[0078] Table 3 shows the results of a third test using the disclosed system, which was operated in a constant voltage mode with a Ni cathode electrode nugget in a 2M sulfuric acid electrolyte solution under incremental temperature changes. The final pH of the solution was 0.10 pH. Ni was not effectively deposited on the cathode electrode. At 60°C, the overall electrical efficiency was 96%. The efficiency of each cycle was at least 95%. It has been found that the dissolution of Ni increases with increasing temperature. A total of 20.2 g of Ni was dissolved in the electrolyte solution.

[0079] Table 3

[0080] Time (hr) Voltage (V) Current (A) Temperature(℃) Ni concentration (g / L) 0 - - - 0 1 2.6 5.9 40 15.1 2 2.7 5.2 50 32.2 3 2.6 6.8 60 51.8

[0081] This example shows that at a constant voltage of 2.6-2.7 volts, the Ni concentration in the electrolyte solution increases from 0 g / l to 51 g / l over three hours.

[0082] Example 4

[0083] Table 4 shows the results of a fourth test using the disclosed system, which was operated in variable voltage mode at a constant voltage with a Ni cathode electrode nugget at a constant temperature in a 1M sulfuric acid electrolyte solution. It was found that there was no deposition of Ni on the cathode electrode. The current drawn was lower relative to the comparative test using a 2M sulfuric acid electrolyte solution. It was found that the efficiency of the system was very high at low voltages. The hot pockets formed on the electrode would cause the electrolyte solvent to evaporate. A total of 10.5 g of Ni was dissolved in the electrolyte solution.

[0084] Table 4

[0085] Time (hr) Voltage (V) Current (A) Temperature(℃) Ni concentration (g / L) 0 - - 50 0 1 1.6 4.7 50 12.9 2 2.7 2.5 50 23.8

[0086] This example shows that in a more dilute 1 M sulfuric acid electrolyte solution, the Ni concentration increases from 0 g / l to 23.8 g / l over 2 hours at 1.6 V and 2.7 V.

[0087] Example 5

[0088] Table 5 shows the results of a fifth test using the disclosed system, which was operated in a variable voltage mode at a constant temperature with a Ni cathode electrode nugget in a 3M sulfuric acid electrolyte solution. It was found that the deposition of Ni was high. It was found that the current drawn was much higher than the comparative test using a 2M sulfuric acid electrolyte solution. It was found that the efficiency of the system was very high. The hot pockets formed on the electrode caused the electrolyte solvent to evaporate. A total of 50g of Ni was dissolved in the electrolyte solution. 1.2g of Ni was deposited on the cathode electrode.

[0089] Table 5

[0090] Time (hr) Voltage (V) Current (A) Temperature(℃) Ni concentration (g / L) 0 - - 50 0 1 2.7 11 50 60 2.5 2.6 8.8 50 82 4.8 3.3 7.3 50 167

[0091] This example shows that in a more concentrated 3M sulfuric acid solution, the Ni concentration in the electrolyte solution increases from 0 g / l to 167 g / l over 4.8 hours at a voltage of 2.7 to 3.3 volts.

[0092] Example 6

[0093] Table 6 shows the test results using the disclosed system with rectangular and cylindrical Ni metal sheets as cathode metal feedstock. Table 6 shows that the surface area of ​​the cathode material directly affects the dissolution of Ni because the cathode electrode area affects the resistance given by the system according to the following equation.

[0094]

[0095] Maintaining the same operating conditions during the experiment should give the understanding that the resistance is imparted by the reaction coordination rather than ohmic resistance. In addition, it has been found that when the area of ​​the cathode is reduced, the increased current is directed towards hydrolysis rather than for the purpose of metal dissolution.

[0096] Table 6

[0097]

[0098] Example 7

[0099] Fig.10 A graph of current versus voltage for a Ni pellet is shown, Fig.11A graph of current versus voltage for a Ni cathode electrode nugget dissolved using the disclosed system is shown. Prior to application of voltage between the cathode and anode, the Ni agglomerate was found to dissolve quite naturally in solution, while the Ni cathode nugget was chemically negligible. Once voltage was applied, high current was observed in the agglomerate, while no pitting was observed, while in the nugget the current density was relatively low and pitting was observed at high voltage. In addition, while a large number of bubbles were observed in the agglomerate, in the nugget the bubbles were limited to the initial stage. The efficiency of dissolution of the agglomerate was found to be 96.5%, while the efficiency of the nugget was 90.6%.

[0100] Example 8

[0101] Fig.12 The dissolution of Ni agglomerates using the disclosed system is shown. Fig.12 As shown, using the system described in this article, Ni agglomerates can be completely dissolved in about five hours by electrochemical methods at 3M sulfuric acid and 50°C.

[0102] Example 9

[0103] Fig.13 Shown are the current versus voltage characteristics of Ni electrochemical dissolution using the disclosed system at 60°C using a 2M sulfided acid electrolyte solution. Fig.13 The region (I) effective dissolution range, (II) passivation voltage range, and (III) super passivation region where oxygen gradually begins to play a leading role in the anodization process are shown. Therefore, it can be seen that the region (I) of about 0V to 1V and the region (III) of about 2V to 3.5V can be used for Ni electrochemical dissolution. However, the region (II) between about 1V and 2V may not dissolve Ni optimally.

[0104] The foregoing disclosure is not intended to limit the disclosure to the precise form disclosed or to the specific field of use. Thus, it is contemplated that various alternative embodiments and / or modifications to the disclosure are possible in accordance with the present disclosure, whether or not explicitly described or implied herein. Thus, having described embodiments of the disclosure, it will be appreciated by those of ordinary skill in the art that changes may be made in form and detail without departing from the scope of the disclosure. Therefore, the disclosure is limited only by the claims.

[0105] In the foregoing description, the present disclosure has been described with reference to specific embodiments. However, as will be appreciated by those skilled in the art, without departing from the spirit and scope of the present disclosure, the various embodiments disclosed herein may be modified or otherwise implemented in various other ways. Therefore, the description should be considered illustrative, and is to teach those skilled in the art to prepare and use the various embodiments of the present disclosure. It should be understood that the disclosed forms shown and described herein will be considered as representative embodiments. Equivalent elements, materials, processes or steps may replace those representatively shown and described herein. In addition, some features of the present disclosure may be utilized independently of the use of other features, all of which will be clear to those skilled in the art who benefit from the description of the present disclosure. Expressions such as "including", "comprising", "incorporating", "consisting of", "having", "is" and the like used to describe and claim the present disclosure are intended to be interpreted in a non-exclusive manner, that is, it is allowed that there are also items, components or elements that are not explicitly described. Mentioning the singular should also be interpreted as involving the plural.

[0106] In addition, various embodiments disclosed herein should be understood in an illustrative and explanatory sense, and should never be interpreted as limitations to the present disclosure. All connection references (e.g., attaching, fixing, coupling, connecting, etc.) are only used to help readers understand the present disclosure, and will not cause limitations, particularly the position, orientation or purpose of the system and / or the limitations of the method disclosed herein. Therefore, connection references (if any) should be interpreted broadly. Moreover, such connection references do not necessarily infer that two elements are directly connected to each other.

[0107] In addition, all numerical terms (such as but not limited to "first", "second", "third", "primary", "secondary", "primary" or any other general and / or numerical terms) should also be regarded as identifiers only to help the reader understand the various elements, embodiments, variations and / or modifications of the present disclosure, and may not create any limitations, especially as to the order or preference of any element, embodiment, variation and / or modification with respect to or compared to another element, embodiment, variation and / or modification.

[0108] It should also be understood that one or more elements depicted in the drawings / figures may also be implemented in a more separate or integrated manner, or even removed or rendered inoperable in some cases, such as according to a specific application. In addition, unless otherwise specifically stated, any signal hatching in the drawings / figures should be considered only as exemplary and not restrictive.

Claims

1. An electrochemical dissolution system for dissolving a metal raw material, comprising: an electrolyte bath container including a container wall and configured to contain an electrolyte solution, the electrolyte bath container including a container wall; Temperature control system; a single liquid permeable anode electrode including an electrically conductive anode electrode body and disposed within the bath vessel; a single cathode electrode continuously surrounding the single liquid permeable anode electrode and equally spaced from the single liquid permeable anode electrode on all sides by a distance of 1 mm to 2 cm; an inlet and an outlet positioned on opposite sides of the electrochemical dissolution system and between the vessel wall and the cathode electrode; as well as A power source is electrically connected to the single liquid permeable anode electrode and the cathode electrode. 2 . The electrochemical dissolution system of claim 1 , further comprising a stirrer configured to stir the electrolyte in the bath container.

3. The electrochemical dissolution system of claim 1, wherein the single liquid permeable anode electrode comprises a basket-type shape, a sandwich-type shape, or a tray-type shape.

4. The electrochemical dissolution system of claim 1, wherein the single liquid permeable anode electrode comprises at least one of: platinum, platinum-coated titanium, and iridium-coated titanium.

5. The electrochemical dissolution system of claim 1, further comprising a metal feedstock immersed in the electrolyte solution and held by the single liquid permeable anode electrode.

6. The electrochemical dissolution system of claim 5, wherein the metal feedstock comprises at least one of the following: a nickel cathode, a nickel agglomerate, a cobalt cathode, and a cobalt agglomerate.

7. The electrochemical dissolution system of claim 1, wherein the single liquid permeable anode electrode comprises an anode electrode body comprising at least one of: a mesh-type material and a perforated-type material.

8. The electrochemical dissolution system of claim 1, wherein the single cathode electrode comprises at least one of: platinum, platinum-coated nickel, and nickel.

9. The electrochemical dissolution system of claim 1, wherein the single cathode electrode comprises a cathode electrode body, the cathode electrode body comprising at least one of: a corrugated material, a sponge material, and an embossed material.

10. The electrochemical dissolution system of claim 1, wherein the electrolyte bath container comprises an electrolyte.

11. The electrochemical dissolution system of claim 10, wherein the electrolyte comprises an acid.

12. The electrochemical dissolution system of claim 11, wherein the acid is sulfuric acid.

13. The electrochemical dissolution system of claim 11, wherein the concentration of the acid is between 1 M and 3 M.

14. The electrochemical dissolution system according to claim 2, wherein the electrolyte bath agitator comprises at least one of the following: a mechanical agitator, a magnetic stirrer, a liquid circulator, and an air agitator.

15. A method of using the electrochemical dissolution system according to claim 1, comprising: applying a voltage between the single liquid permeable anode electrode and the cathode electrode; providing fresh electrolyte solution to the electrolyte bath container through the inlet; as well as The treated solution is removed from the electrolyte bath container through the outlet.

16. The method of claim 15, wherein the fresh electrolyte solution has a metal concentration that is less than the metal concentration of the treated solution.

17. The method of claim 15, further comprising controlling the temperature of the electrolyte bath container between 35°C and 60°C using the temperature control system.

18. The method of claim 15, applying a voltage between 2.0V and 3.5V.

19. The method of claim 15, applying a voltage between 0.1V and 1V.

20. The electrochemical dissolution system of claim 1, wherein the electrochemical dissolution system is configured to operate at atmospheric pressure.

21. The electrochemical dissolution system of claim 1, wherein the system is a continuous system.

22. The electrochemical dissolution system of claim 1, wherein the system is configured to continuously flow fresh electrolyte solution into the system and continuously drain treated electrolyte solution from the system.

23. The method of claim 15, wherein providing the fresh electrolyte solution comprises continuously providing the new electrolyte solution through the inlet.

24. The method of claim 15, wherein extracting the treated solution comprises continuously extracting the treated solution through the outlet.

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